A conventional spectacle structure, such as a pair of general optical eyeglasses, usually includes a lens frame, two lenses, and two temples. The lens frame includes two frame members for receiving the two lenses therein, such that the two lenses are separately fitted into the two frame members. The two temples are separately pivotally connected to two laterally outer frame sections of the two frame members. When it is desired to add a soft pad or a wind guard to a rear side of the lens frame for the pair of eyeglasses to be more comfortable for wearing or to prevent crosswind from directly blowing into a user's eyes, an adhesive structure, a clip-on structure, or a magnetic structure is usually used to connect the soft pad or the wind guard to the rear side of the lens frame. However, either the adhesive structure or the clip-on structure or the magnetic structure is an external structure that not only increases the whole structural complexity and accordingly, the manufacturing cost of the eyeglasses, but also is inconvenient for use. For example, for the soft pad or wind guard to be firmly attached to the rear side of the lens frame of the eyeglasses, the above-mentioned adhesive, clip-on, or magnetic structure would usually have to possess relatively high adhesion, clipping force, or magnetic attraction force. The high adhesion, clipping force, or magnetic attraction force would prevent a user from conveniently detaching the soft pad or the wind guard from the lens frame.
Therefore, it is desirable to develop a spectacle structure having an inner frame unit and a lens unit that can be firmly assembled to and conveniently disassembled from each other.